603 SKIN MICROBIOME INNOVATIONS
Concentration (MBEC) assay for accurate assessment. This assay utilizes a Calgary Biofilm
Device for screening antibiotics and biocides for their efficacy against microbial biofilms.
This system is particularly useful for screening potential new antibiotics or biocides or
determining both the MIC and MBEC values in clinical contexts, such as treating chronic,
recurrent, or device-associated infections.15
MIC readings have proven invaluable in therapeutic treatments and are now being
integrated into the personal care industry using natural antimicrobials. For instance,
knowing the MIC value needed to inhibit C. acnes, the bacteria responsible for acne, or
Malassezia furfur, the fungus causing dandruff and seborrheic dermatitis, can guide product
development. To connect with personal care consumers, presenting a clear problem-and-
solution approach is essential: identify the microbes causing their issue, and recommend
products with ingredients that target and reduce those microbes. This method resonates
well enough with consumers, but there is a new innovative solution on the horizon that
could unify and streamline this information even further.
DERMAL MICROBIOME-IMMUNOLOGY ASSAY
With known methods of microbiome analysis that perhaps have not quite hit the mark
on effectively communicating latest information, the exciting thing about research and
uncharted landscapes is the opportunity to revolutionize the new standard for delivery.
This white space is what fueled the innovation for an assay that would allow brands to
have a pivotal role in the up-and-coming microbiome space. As previously mentioned,
dendritic cells are the sentinels of the immune system and it turns out that these cells
can easily be propagated in vitro using a multitude of growth factors, such as granulocyte
macrophage-colony stimulating factors (GM-CSF). Based on the knowledge that dendritic
cells release signals that notify the body’s immune system to start working, this new assay
Table I
Final Antibiotic Susceptibility Report for Klebsiella pneumoniae13
MIC (mcg/mL) Interpretation
Amikacin ≤2 S
Ampicillin ≥32 R
Ampicillin/Sulbactam 16 I
Cefazolin ≥64 R
Cefepime 2 R
Ceftriaxone ≥64 R
Ciprofloxacin ≥64 R
ESBL (Extended-Spectrum Beta-Lactamases) NEG
Gentamicin ≥16 R
Imipenem ≤1 S
Piperacillin ≥128 R
Piperacillin/Tazobactam 1.5 S
Tigecycline ≤0.5 S
Tobramycin 8 I
Trimethoprim/Sulfamethoxazole ≥320 R
*Redrawn from Kowalska-Krochmal.13 I: Intermediate R: Resistant
S: Susceptible.

604 JOURNAL OF COSMETIC SCIENCE
was developed on the premise that these signals can be modulated. Would it be possible to
signal the human body to reestablish its own microbiome harmony?
The Dermal Microbiome-Immunology Assay is designed to assess the effect of active
ingredients used in the personal care industry to alter dendritic cell paracrine signaling
molecules to kill detrimental organisms found on the skin but leave alone the commensal
microbiota as to not disrupt the beneficial skin environment. This addresses the common
misconception that all bacteria are bad bacteria. The skin needs commensal, or “good,”
bacteria for crucial mechanisms to function properly. For this reason, it is important to
note that for the below assay, a reduction in all microbes would not be ideal. Table II below
describes the microorganisms that are examined in the Dermal Microbiome-Immunology
Assay, along with their importance.
METHODS OF THE DERMAL MICROBIOME-IMMUNOLOGY ASSAY
Human CD14+ Monocytes (PromoCell, C-12909) are thawed and seeded with an
appropriate amount of complete Dendritic Cell Generation Medium (Complete Media)
(PromoCell, C-28050) and supplemented with Component A of the Cytokine Pack moDC
(PromoCell, C-28050). Twenty-four hours later, the culture media is replaced with fresh
complete Dendritic Cell Generation Medium supplemented with 1x Component A of the
Cytokine Pack moDC. After three days, culture media is replaced again. Twenty-four
hours later, Component B of the Cytokine Pack moDC (PromoCell, C-28050) is added to
culture media and allowed to incubate for an additional 48 hours. Following the two-day
incubation, the mature dendritic cells are harvested and cryopreserved.
After a 24-hour attachment period, the complete media is replaced with 5 milliliters of
either the complete media, which functioned as the control, or differing concentrations of
an antimicrobial-free cosmetic active diluted with complete media. Notably, the Dendritic
Cell Generation Medium is also free of antimicrobial agents. Then, after the dendritic cells
are exposed to experimental conditions for 24 hours, the conditioned media is collected and
stored at −80° Celsius until the time kill test is performed.
For the time kill test, one milliliter of the test article is loaded into a sterile disposable
polypropylene tube. Each container is inoculated with one of the three bacteria organisms
presented in Table I. The inoculum concentration for each bacterium is standardized using
the 0.5 McFarland turbidity standard and is further diluted to yield approximately 106
microorganisms/mL. The amount of each inoculum added to the samples is no more than
1.0% of the product volume to ensure the composition is not altered. Serial dilutions from
each container are performed to enumerate the surviving microorganisms using the plate
Table II
The Microorganisms Examined and Their Importance
Microorganism Type Importance
Staphylococcus aureus Gram-positive Human opportunistic pathogen with antibiotic resistant
strains
Pseudomonas aeruginosa Gram-negative Human opportunistic pathogen and used to study
antibiotic resistance and pathogenesis
Staphylococcus epidermidis Gram-positive An element of normal skin microbiota, nonpathogenic, and
supports dermal barrier integrity